58 THE CHICAGO ACADEMY OF SCIENCES. 



2. Canadian. This area includes the drainage system of the 

 St. Lawrence, including the Great Lakes and their tributary streams. 

 All of Quebec and Ontario south of the "Height of Land" is included 

 as well as the Island of Anticosti. 



3. Hudsonian. This region includes the area draining into 

 Hudson Bay, embracing the basins of the English, Saskatchewan, Al- 

 bany, Severn and the Red River of the North, besides numerous minor 

 streams. This territory, which is the largest of the areas here defined, 

 embraces the western portion of Ungava, the southeastern portion of 

 Mackenzie, the whole of Keewatin, eastern Athabaska, the whole of 

 Saskatchewan, Assiniboia and Manitoba, the southern part of Alberta, 

 Ontario and Quebec northwest of the "Height of Land," the northern 

 part of Minnesota and the eastern part of North Dakota. The divide, 

 known as the "Height of Land" divides North America into two huge 

 areas, the rivers in the northern part flowing to the north, while the 

 rivers south of this divide flow southward. 



4. Mackenzian. This area includes the greater part of Mac- 

 kenzie district, the central and western part of Athabaska, northwestern 

 Alberta and northeastern British Columbia. It embraces the Mackenzie 

 River and its tributaries. 



5. Yukonian. This region includes the drainage system of the 

 Yukon River, together with the smaller rivers lying north and north- 

 west of the Alaskan mountain range. It embraces the whole of Yukon 

 district and all of Alaska north of the Alaskan range. 



6. Alaskan. This small area includes all of the coastal region 

 lying south and west of the Alaskan range and the coast range as far 

 south as Vancouver Island, and including the Alaska Peninsula and 

 the Aleutian Islands. While this region is, as stated by Dall, closely 

 related to the Columbian Region, its separation from that region and 

 from the Yukonian by an extensive mountain chain would seem to 

 warrant its separation as a regional division. 



7. Columbian. This area includes the basins of the Fraser and 

 the Columbia rivers, including the Snake River and its tributary 

 streams. The territory embraces the southeastern part of British 

 Columbia, the whole of Washington and Idaho, the western part of 

 Montana and the eastern part of Oregon. The headwaters of tributary 

 streams touch Wyoming and Nevada. 



8. Coloradoan. This includes the entire drainage of the Colo- 

 rado River, including the basin of the Gila River. Geographically it 

 embraces the southern part of Nevada and Utah, the western parts 

 of Colorado and New Mexico, the southwestern part of Wyoming, a 



